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United States Patent |
6,099,328
|
Nelson
,   et al.
|
August 8, 2000
|
High-speed edge connector
Abstract
An electrical edge connector and a terminal therefore for connecting a
first electrical circuit board to a second electrical circuit board, the
first electrical circuit board having an insertion edge and two sides, the
connector comprising an elongated dielectric housing having therein a
longitudinal slot for receiving the insertion edge of the first electrical
circuit board and a plurality of transverse terminal receiving cavities
adjoining the slot on each side of the slot, and a plurality of signal
terminals disposed within some of the terminal retention cavities on each
side of the slot and a plurality of ground terminals disposed within
others of the terminal retention cavities on each side of the slot, the
signal and ground terminals each having a base portion, a retention
portion extending from the base portion and retaining the terminal in one
of the retention cavities, a tail portion extending from the base portion
for electrically connecting the terminal to the second electrical circuit,
and a spring arm connected to the base portion for electrically connecting
the terminal to the first electrical circuit board, the ground terminals
including a generally tapered, enlarged surface area portion for enhancing
electrical coupling between the ground terminal and an adjacent signal
terminal.
Inventors:
|
Nelson; Richard A. (Geneva, IL);
Brunker; David L. (Naperville, IL)
|
Assignee:
|
Molex Incorporated (Lisle, IL)
|
Appl. No.:
|
082834 |
Filed:
|
May 21, 1998 |
Current U.S. Class: |
439/101; 439/637 |
Intern'l Class: |
H01R 004/66 |
Field of Search: |
439/101,108,637,60,608
|
References Cited
U.S. Patent Documents
3871728 | Mar., 1975 | Goodman | 339/14.
|
4806103 | Feb., 1989 | Kniese et al. | 439/637.
|
4993972 | Feb., 1991 | Lin | 439/637.
|
5112231 | May., 1992 | Harwath et al. | 439/60.
|
5192220 | Mar., 1993 | Billman et al. | 439/327.
|
5249988 | Oct., 1993 | Lu | 439/751.
|
5259768 | Nov., 1993 | Brunker et al. | 439/60.
|
5309630 | May., 1994 | Brunker et al. | 29/842.
|
5393234 | Feb., 1995 | Yamada et al. | 439/62.
|
5522737 | Jun., 1996 | Brunker et al. | 439/60.
|
5580257 | Dec., 1996 | Harwath | 439/637.
|
5730609 | Mar., 1998 | Harwath | 439/637.
|
Primary Examiner: Paumen; Gary F.
Attorney, Agent or Firm: Cohen; Charles S.
Claims
What is claimed is:
1. An electrical edge connector for electrically and mechanically
connecting a first electrical circuit board to a second electrical circuit
board, said first electrical circuit board having an insertion edge and
two generally planar faces, said connector comprising:
an elongated dielectric housing having therein a longitudinal slot for
receiving said insertion edge of said first electrical circuit board and a
plurality of transverse terminal receiving cavities adjoining said slot on
each side of said slot; and
a plurality of signal terminals disposed within some of said terminal
receiving cavities on each side of said slot and a plurality of ground
terminals disposed within others of said terminal receiving cavities on
each side of said slot, said signal and ground terminals each having a
base portion, a retention portion extending from said base portion and
retaining said terminal in one of said retention cavities, a tail portion
extending from said base portion for electrically connecting said terminal
to said second electrical circuit board, and a spring arm connected to
said base portion for electrically connecting said terminal to said first
electrical circuit board;
said base portion of each said ground terminal including a first generally
rectangular section extending generally along a lower surface of said
housing, a second generally rectangular section extending up from said
first generally rectangular section, a portion of said second generally
rectangular section extending along a portion of said slot, and a
generally tapered, enlarged surface area portion extending from said
second generally rectangular section for enhancing electrical coupling
between said ground terminal and an adjacent signal terminal.
2. An electrical edge connector in accordance with claim 1 wherein said
spring arm of each said ground terminal includes an upwardly and inwardly
inclined portion spaced generally along said tapered, enlarged surface
area portion.
3. An electrical edge connector in accordance with claim 1 wherein each
said ground terminal includes two tail portions extending from said base
portion for electrically connecting said terminal to said second
electrical circuit board.
4. An electrical edge connector in accordance with claim 3 wherein one of
said two terminal portions is for surface mounting to said second
electrical circuit board and another one of said two terminal portions is
for mounting to said second electrical circuit board in through-hole
fashion.
5. An electrical edge connector in accordance with claim 3 wherein said
ground terminal has exactly two tail portions, and said contact portion
meets said base portion approximately equidistantly from where said two
tail portions meet said base portion.
6. An electrical edge connector in accordance with claim 1 wherein said
enlarged surface area portion is a generally triangularly shaped portion
extending up from said second generally rectangular section and wherein
said spring arm of said ground terminal includes an upwardly and inwardly
inclined portion spaced generally evenly from said generally triangularly
shaped portion.
7. A terminal for an electrical edge connector for connecting a first
electrical circuit board to a second electrical circuit board, wherein
said first electrical circuit board has an insertion edge and two
generally planar faces and said connector has an elongated dielectric
housing having therein a longitudinal slot for receiving said insertion
edge of said first electrical circuit board and a plurality of transverse
terminal receiving cavities adjoining said slot on each side of said slot,
said terminal comprising:
a base portion, including a first generally rectangular section extending
generally along a lower surface thereof, a second generally rectangular
section extending up from said first generally rectangular section, a
portion of second generally rectangular section configured to extend along
a portion of said slot, and a generally tapered, enlarged surface area
portion extending from said second generally rectangular section for
enhancing electrical coupling between said terminal and an adjacent signal
terminal;
a retention portion extending from said base portion for retaining said
terminal in one of said receiving cavities;
a tail portion extending from said base portion for electrically connecting
said terminal to said second electrical circuit board; and
a spring arm connected to said base portion for electrically connecting
said terminal to said first electrical circuit board, said spring arm
including an upwardly and inwardly inclined portion spaced generally
evenly along said tapered, enlarged surface area portion.
8. A terminal in accordance with claim 7 wherein said terminal comprises
two tail portions extending from said base portion for electrically
connecting said terminal to said second electrical circuit board.
9. A terminal in accordance with claim 8 wherein one of said two terminal
portions is for surface mounting to said second electrical circuit board
and another one of said two terminal portions is for mounting to said
second electrical circuit board in through-hole fashion.
10. A terminal in accordance with claim 8 having exactly two tail portions,
said spring arm meeting said base portion approximately equidistantly from
where said two tail portions meet said base portion.
11. A terminal in accordance with claim 8 wherein said enlarged surface
area portion is a generally triangularly shaped portion extending up from
said second generally rectangular section and wherein said upwardly and
inwardly inclined portion of said ground terminal is generally evenly
spaced from said generally triangularly shaped portion.
12. An electrical edge connector for electrically and mechanically
connecting a first electrical circuit board to a second electrical circuit
board, said first electrical circuit board having an insertion edge and
two generally planar faces, said connector comprising:
an elongated dielectric housing having therein a longitudinal slot for
receiving said insertion edge of said first electrical circuit board and a
plurality of transverse terminal receiving cavities adjoining said slot on
each side of said slot; and
a plurality of signal terminals disposed within some of said terminal
receiving cavities on each side of said slot and a plurality of ground
terminals disposed within others of said terminal receiving cavities on
each side of said slot,
each said signal terminal having a base portion, a retention portion
extending from said base portion and retaining said signal terminal in one
of said retention cavities, a tail portion extending from said base
portion for electrically connecting said terminal to said second
electrical circuit board, and a spring arm connected to said base portion
for electrically connecting said terminal to said first electrical circuit
board;
each said ground terminal having a base portion including a first generally
rectangular section extending generally along a lower surface of said
housing, a second generally rectangular section extending up from said
first generally rectangular section, a portion of second generally
rectangular section extending along a portion of said slot, and a
generally tapered, enlarged surface area portion extending from said
second generally rectangular section for enhancing electrical coupling
between said ground terminal and an adjacent signal terminal, said ground
terminal further having a retention portion extending from said base
portion and retaining said ground terminal in one of said retention
cavities, a tail portion extending from said base portion for electrically
connecting said terminal to said second electrical circuit board, and a
spring arm connected to said second generally rectangular section for
electrically connecting said terminal to said first electrical circuit
board, said spring arm including an upwardly and inwardly inclined portion
spaced generally evenly from said tapered, enlarged surface area portion.
13. An electrical edge connector in accordance with claim 12 wherein each
said ground terminal includes two tail portions extending from said base
portion for electrically connecting said terminal to said second
electrical circuit board.
14. An electrical edge connector in accordance with claim 13 wherein one of
said two terminal portions is for surface mounting to said second
electrical circuit board and another one of said two terminal portions is
for mounting to said second electrical circuit board in through-hole
fashion.
15. An electrical edge connector in accordance with claim 13 wherein said
ground terminal has exactly two tail portions, and said contact portion
meets said base portion approximately equidistantly from where said two
tail portions meet said base portion.
16. An electrical edge connector in accordance with claim 12 wherein said
enlarged surface area portion is a generally triangularly shaped portion
extending up from said second generally rectangular section and wherein
said upwardly and inwardly inclined portion of said ground terminal is
generally evenly spaced from said generally triangularly shaped portion.
Description
BACKGROUND OF THE INVENTION
The invention pertains generally to electrical connectors for computers,
and more specifically to high-speed edge connectors for mechanically and
electrically connecting electrical circuits, such as two printed circuit
boards.
As computers continue to process data at ever-increasing rates, "bus" type
electrical connectors, such as those electrically connecting a processor
to random access memory, are being asked to provide increasingly higher
data transfer rates through increasingly smaller spaces. In particular,
there is pressure to reduce the size of the connectors while increasing
the data throughput.
However, countervailing mechanical and electrical performance
considerations have continued to inhibit very high data transfer rates. In
general, short, thick terminals are capable of providing lower inductance
and thereby enhancing electrical performance. This can be achieved through
ample surface area and minimal series path impedance, so as to minimize
signal degradation. Mechanically, however, longer, thinner terminals are
generally preferable to retain contact flexibility, facilitate mating
criteria, and meet pitch/density specifications.
Thus, there is a demand for denser edge connectors having faster data
transfer rates while not sacrificing mechanical integrity or signal
quality. A dense array of parallel paths, however, can result in
significant signal-degrading cross-talk and/or undesirable levels of
electromagnetic interference.
SUMMARY OF THE INVENTION
The inventive electrical connector and terminals, disclosed and claimed
herein, significantly improve data transfer rates between electrical
circuits without substantial signal degradation, electromagnetic
interference, or mechanical weakening. The terminals have been designed
particularly to minimize impedance and signal degradation while not
significantly diminishing mechanical strength, and the particular
terminals have been strategically arranged within the connector to further
minimize cross-talk and electromagnetic interference.
In one aspect of this invention, there is provided an electrical edge
connector for electrically and mechanically connecting a first electrical
circuit board to a second electrical circuit board, the first electrical
circuit board having an insertion edge and two sides. The connector
includes an elongated dielectric housing having therein a longitudinal
slot for engaging the insertion edge of the first electrical circuit board
and a plurality of transverse terminal receiving cavities adjoining the
slot on each of its sides, a plurality of signal terminals disposed within
some of the terminal receiving cavities on each side of the slot and a
plurality of ground terminals disposed within others of the terminal
receiving cavities on each side of the slot. The signal and ground
terminals each have a base portion, a retention portion extending from the
base portion for retaining the terminal in one of the receiving cavities,
a tail portion extending from the base portion for electrically connecting
the terminal to the second electrical circuit board, and a spring arm
connected to the base portion for electrically connecting the terminal to
the first electrical circuit board, wherein each ground terminal includes
a generally tapered, enlarged surface area portion extending from its base
portion adjacent the spring arm for enhancing electrical coupling between
the ground terminal and an adjacent signal terminal.
In another aspect of this invention, there is provided an electrical edge
connector for electrically and mechanically connecting a first electrical
circuit board to a second electrical circuit board, the first electrical
circuit board having an insertion edge in two sides. In this aspect, the
connector includes an elongated dielectric housing having therein a
longitudinal slot for engaging the insertion edge of the first electrical
circuit, a plurality of transverse terminal receiving cavities adjoining
the slot on each side of the slot, and a plurality of first, second, and
third terminals each disposed within some of the terminal receiving
cavities on each side of the slot. Each of the three distinct terminals
has a base portion, a retention portion extending from the base portion
for retaining the terminal in one of the receiving cavities, a tail
portion extending from the base portion for electrically connecting the
terminal to the second electrical circuit, and a spring arm connected to
the base portion for electrically connecting the terminal to the first
electrical circuit.
Yet another aspect of the invention is a terminal for use in an electrical
edge connector for connecting a first electrical circuit board to a second
electrical circuit board, wherein the first electrical circuit board has
an insertion edge and two sides and said connector has an elongated
dielectric housing having therein a longitudinal slot for engaging the
insertion edge of the first electrical circuit and a plurality of
transverse terminal receiving cavities adjoining the slot on each side of
the slot. The terminal includes a base portion, a retention portion
extending from the base portion for retaining the terminal in one of the
receiving cavities, a tail portion extending from the base portion for
electrically connecting the terminal to the second electrical circuit
board, a spring arm connected to the base portion for electrically
connecting the terminal to the first electrical circuit board, and a
tapered, enlarged surface area portion extending upwardly from the base
portion adjacent the spring arm for enhancing electrical coupling between
the terminal and an adjacent terminal.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of the inventive edge connector and
terminals as seen in their general environment for application;
FIG. 2 is a cross-sectional view of the connector of FIG. 1 as taken
generally along line 2--2;
FIG. 3 is a cross-sectional view of the connector of FIG. 1 as taken
generally along line 3--3;
FIG. 4 is a front elevational view of a ground terminal in accordance with
the invention;
FIG. 5 is a front elevational view of a low terminal in accordance with the
invention;
FIG. 6 is a front elevational view of a middle terminal in accordance with
the invention; and
FIG. 7 is a broken, schematic plan view of the arrangement of distinct
terminals within the terminal retention cavities of the inventive
connector.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of the invention is a connector 10 for
electrically and mechanically connecting a first electrical circuit on
edge card 20 to a second electrical circuit on motherboard 30. As seen in
exploded view in FIG. 1, the connector includes a dielectric housing 12
defining a longitudinal slot 13 and a plurality of transversely oriented
terminal retention cavities 14 on both sides of the slot 13. The terminal
receiving cavities 14 are defined at least in part by transverse walls 15
that extend from sidewalls 16 towards slot 13. While not necessary to the
invention or shown in the drawings, the preferred embodiment additionally
has mounting pegs (not shown) on the bottom of the housing 12 for
facilitating mounting of the connector onto the motherboard 30. Keys 18
preferably provide additional structural stability to the connector and
facilitate alignment of the edge card 20 within the longitudinal slot 13
of the connector.
FIG. 1 also shows the edge card 20 having an insertion edge 22 for
inserting into the longitudinal slot 13 of the connector. The insertion
edge 22 preferably has notches or keyways 24 for engaging the keys 18 upon
insertion of the edge card 20 into the longitudinal slot 13. The alignment
of the keyways 24 and the keys 18 facilitates alignment between the edge
card 20 and housing 12, and may also provide for polarization to prevent
insertion of the edge card 20 in an improper orientation. The edge card 20
has oppositely facing generally planar surfaces 26 with pads 28 or other
forms of electrical contacts proximate the insertion edge 22. The pads 28
are sufficiently near the insertion edge 22 such that they are at least
partially inside the longitudinal slot 13 of the housing 12 when the edge
card 20 has been fully inserted therein.
The connector is preferably mounted onto and aligned with the motherboard
30 by inserting the mounting pegs (not shown) attached to the bottom of
the housing 12 into appropriately sized apertures (not shown) in the
motherboard 30. The motherboard 30 may electrically interface with the
connector by a plurality of through-holes 32 extending through the board
and/or by a plurality of traces 34 or other surface-type electrical pads
thereon.
As seen in FIGS. 4-6, the preferred embodiment of the invention has
terminals of three distinct types for insertion into and retention within
terminal retention cavities 14. The preferred embodiment of the invention
has a plurality of ground or power terminals 40 (FIG. 4), low terminals 60
(FIG. 5), and middle terminals 70 (FIG. 6). It is not necessary to the
invention that the ground terminal 40 is a dedicated ground terminal or
that the low and middle terminals 60 and 70 are dedicated signal
terminals. However, they are referred to in this manner herein for
clarity.
The ground terminal 40 preferably has a generally horizontal base portion
42 having several other portions extending therefrom. In particular,
extending from the base portion 42 is a retention portion 44 having barbs
45 for retaining the ground terminal 40 within its associated terminal
retention cavity by digging into the housing, a through-hole tail portion
46 for extending through and electrically connecting to a through-hole 32
in the motherboard 30, a surface-mount tail portion 48 having an enlarged
foot 49 for electrically engaging a trace or pad 34 on the motherboard 30,
a spring arm portion 50 having a contact portion 54 for electrically
engaging the pads 28 on the sides 26 of the edge card 20, and an enlarged
surface area portion 56. The enlarged surface area portion 56 preferably
has a substantially rectangular portion 57 and an upwardly extending,
generally tapered triangular-shaped portion 58. The enlarged surface area
portion 56 facilitates electrical coupling between the particular ground
terminal 40 and an adjacent terminal. This form of coupling is
particularly useful in enhancing the cross-coupling between ground/power
and adjacent signal terminals and diminishing the cross-coupling between
adjacent signal terminals in the preferred embodiment.
The enlarged surface area portion 56 also enables the ground terminal 40 to
carry larger current, as is often required in a ground/power application.
Having two connections to the motherboard 30 as it does with the
through-hole tail portion 46 and the surface-mount tail portion 48 also
facilitates a larger aggregate current by splitting the current through
these two paths to the motherboard. In this embodiment, the two tail
portions 46 and 48 are approximately equidistantly disposed from the main
current path of the ground terminal 40, namely where the spring arm
portion 50 meets the base portion 42 approximately at the center of the
base portion 42. The approximately equidistant disposition has the benefit
of dividing the current nearly evenly between the two pathways due to
nearly equal impedance.
The spring arm portion 50 preferably includes a vertical portion 51
extending from the rectangular portion 57 of the enlarged surface area
portion 56 and in a direction away from the base portion 42 of the ground
terminal 40, an inwardly angled portion 52 extending further upwardly from
the end of the vertical portion 51 to a contact portion 54, the most
inwardly projecting section of the spring arm portion 50, and an outwardly
angled portion 53 extending further upwardly and generally outwardly from
the contact portion 54. This outwardly angled portion 53 is tapered to act
as a lead-in and to permit smooth deflection of spring arm portion 50 by
insertion edge 22 of edge card 20. The tip 55 of the terminals 40 is also
intended to be captured between transverse walls 15 of terminal receiving
cavity 14 to minimize side deflection of the terminal.
The low terminal 60, shown in detail in FIG. 5, preferably has a base
portion 61, a retention portion 62 extending upwardly therefrom, a surface
mount tail portion 64 extending downwardly and outwardly from the outer
end of the base portion 61, and a spring arm portion 66 projecting
upwardly and inwardly from the base portion 61. The retention portion 62
preferably has barbs 63 for retaining the low terminal 60 in its
appropriate terminal retention cavity. The surface-mount tail portion 64
preferably has a foot 65 for electrically connecting in surface-mount
fashion the low terminal 60 to a trace or pad 34 on the surface of the
motherboard 30. The spring arm portion 66 of the low terminal 60
preferably has an inwardly angled portion 67 extending upwardly and
inwardly from the base portion 61 to a contact portion 69, the most
inwardly projecting point of the spring arm portion 66. Extending further
upwardly and outwardly from the contact portion 69 is an outwardly angled
portion 68 and tip 68' for the same purposes as described above with
respect to outwardly angled portion 53 and tip 55 of ground terminal 40.
The middle terminal 70, shown in detail in FIG. 6, preferably has a base
portion 71, a retention portion 72 extending upwardly therefrom, a surface
mount tail portion 74 extending downwardly and outwardly from the outer
end of the base portion 71, and a spring arm portion 76 projecting
upwardly and inwardly from the base portion 71. The retention portion 72
preferably has barbs 73 for retaining the middle terminal in its
appropriate terminal retention cavity. The surface-mount tail portion 74
preferably has a foot 75 for electrically connecting in surface-mount
fashion the middle terminal 70 to a trace or pad 34 on the surface of the
motherboard 30. The spring arm portion 76 of the middle terminal 70
preferably has an inwardly angled portion 77 extending upwardly and
inwardly from the base portion 71 to a contact portion 79, the most
inwardly projecting point of the spring arm portion 76. Extending further
upwardly and outwardly from the contact portion 79 is an outwardly angled
portion 78 and a tip 78' of the spring arm portion 76 in the preferred
embodiment. As such, the middle terminal 70 is substantially identical to
low terminal 60 except that spring arm portion 76 of terminal 70 is longer
and has a different slope than spring arm portion 66 of terminal 60.
As shown schematically in FIG. 8, the three distinct terminals 40, 60, and
70 are strategically placed within terminal retention cavities 14 on each
side of the longitudinal slot 13. In particular, the three distinct
terminals are each used exactly once in a repeated sequence on each side
of the slot 13. In the preferred embodiment, the sequences run in opposite
directions on each side of the slot from any pair of low terminals 60 that
are aligned opposite one another across the slot 13. In accordance with
that arrangement, each middle terminal 70 is thereby opposed by a ground
terminal 40 and each ground terminal is opposed by a middle terminal.
This strategic arrangement provides for exactly one low signal terminal and
one middle signal terminal between each pair of adjacent large dedicated
ground terminals on each side of the slot. The strong coupling tendencies
of the large ground terminals and their enlarged surface areas tend to
electrically isolate the interposed adjacent signal terminals and thereby
diminish cross-talk therebetween. Furthermore, the differentiated heights
of the terminals, as shown in FIGS. 2 and 3, in particular the adjacent
low and middle signal terminals 60 and 70, and the different slopes of the
spring arm portions of the terminals also reduce the cross-coupling
therebetween.
FIGS. 2 and 3 show cross-sectional views perpendicular to the longitudinal
slot 13 to show the differing heights and angles of the contact arms of
the three distinct terminals. It can also be seen therein how the barbed
retention portions retain the terminals in their respective terminal
retention cavities. The staggered heights not only diminish
cross-coupling, but also serve to stagger the insertion forces when the
edge card 20 is inserted into the longitudinal slot 13, thereby
diminishing the maximum insertion force.
The preferred embodiment of the invention, as described above, provides
significant advantages over previous connectors, particularly with regard
to the increased speed of the connector. From the foregoing, it will be
appreciated that the invention provides a novel, high-speed edge connector
for mechanically and electrically connecting electrical circuits. The
invention is not limited to the preferred embodiment described herein, or
to any particular embodiment. Specific examples of alternative embodiments
considered to be within the scope of the invention include embodiments
wherein the three distinct terminals may have different shapes than those
described herein. The terminals may have different functions within the
connector, such as wherein they do not specifically carry the ground/power
and/or signal loads ascribed to them in the preferred embodiment, wherein
the distinct terminals are strategically placed differently within the
terminal retention cavities of the housing, and wherein the various
terminals have alternative combinations of through-hole and/or
surface-mount tails. Other modifications to the preferred embodiment may
also be made within the scope of the invention. The invention is defined
by the following claims.
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